Method of forming a cross linked foamed polyolefin composite article

ABSTRACT

A method for forming soft, resilient, smooth, energy dissipating articles from foamed partially cross-linked polyolefins wherein sheet stock is cut into a preform and the preform while at room temperature is positioned within a mold cavity formed by partible mold halves. The preforms and the cavity of the molds are so arranged and constructed that after molding there is no flashing needing trimming because the polyolefin is substantially confined within the cavity without any lateral projection into the parting surfaces of the mold.

TECHNICAL FIELD

The present invention relates to the manufacture of cushioning, orenergy absorbing, materials such as, for example, that traditionallyused in athletic equipment. Even more particularly the present inventionrelates to methods of molding a moldable, cross-linked, foamedpolyolefin. The present invention is also directed to methods forproducing tenaciously bonded laminates of cross-linked closed-cellfoamed polyolefin in which one of the laminate layers has a densitydifferent than the other laminate layer.

BACKGROUND ART

Articles have been manufactured in the past from foamed, cross-linkedpolyolefin wherein such articles were intended for use as shockabsorbing, or cushioning members, in a wide variety of applications,including athletic equipment. Such members have been manufactured byothers by a process wherein a panel, or sheet-stock, of foamedcross-linked polyolefin (FXLPO), particularly polyethylene, is heated toan elevated temperature and this preheated material then manuallypositioned within a mold in such manner that a peripheral portion isclamped and sealed in the parting line of complimentary partible moldelements. The material can be further heated and either vacuum molded orcompression molded to a preselected shape. It will be appreciated thatdifficulty is encountered in handling such heated sheet stock because ofthe tacky, adhesive and cohesive nature of the heated FXLPO material.Quite commonly in manually handling the heated FXLPO panel, portionsthereof stick together prior to proper positioning in the mold, henceresulting in a situation where an acceptable product can not bemanufactured and material is wasted. Additionally, because cf theclamping of the peripheral boundary of the panel in the mold partingline a great deal of waste flashing is created and must be removed.This, of course, uneconomically increases labor costs and materialcosts.

The problems noted above are common in forming various pads for sportsand athletic equipment such as, for example, hip pads, thigh pads, andknee pads for football equipment. The laterally extending flashingproblem in forming such pads is particularly troublesome from a laborand wasted material point of view.

Present hip pad configurations for use with football equipment,generally have substantially raised, somewhat centrally located portionsextending outwardly from a base portion. With the above-describedmanufacturing techniques currently employed, it is expensive to formsuch raised portions of a material which is not the same as the materialof the base portion of the hip pad. That is, because of the difficultyin handling the tacky, hot sheet stock and the problem of accuratelymanually positioning, and indexing, a different material unto such atacky material, such pads are unitarily formed from a single piece ofsheet stock. It would be desirable to have a process wherein such hippads could be formed with the raised portion and base portion being ofdifferent materials.

In manufacturing thigh pads by the above process there currently is aproblem with regard to unacceptable entrapment of air during forming andalso difficulty in properly indexing the components used to form thesepads. Such thigh pads typically would be formed by first positioning aheated panel of cross-linked, foamed polyolefin in a mold portion,followed by positioning a rigid plastic insert upon the preheated panel.This, in turn, would then be followed by positioning another panel ofheated, foamed, cross-linked polyolefin onto the plastic insert in amanner so as to both encapsulate the insert between the two panels, andjoin the panels at their periphery. The materials would then beperipherally clamped at a mold parting line. This technique, because ofthe adhesive nature of the heated panels, obviously creates an airentrapment problem if the air is not removed as the laminate is beingbuilt up. The removal of such air when handling the sticky, heatedpanels is indeed, a difficult task. The entrapped air then creates airpockets during molding, resulting in a product which could beunacceptable. Indexing is also quite difficult when one considers thesticky, adhesive and cohesive characteristics of the FXLPO which isbeing handled. Both of these problems contribute to poor quality,increased labor costs and increased wasted material.

Thus it will be seen that there is a need in the art for providing aprocess wherein products can be formed without encountering theundesired sticking problem which results when handling heated, foamed,cross-linked polyolefin. A process is also needed wherein the undesiredformation of laterally extending flashing during the molding operationis virtually eliminated. A process is also needed wherein laminates canbe formed such as, for example, thigh pads without encountering severeair entrapment problems between the various layers.

DISCLOSURE OF THE INVENTION

In accordance with the present invention an improved process is providedwhich satisfies the above indicated needs in the art.

In accordance with one feature of the present invention a process isprovided for forming a soft resilient self-supporting energy-dissipatingarticle in a mold having partible mold portions, the mold when in aclosed position, defining an article forming cavity which includes asmooth arcuate edge and said mold having a peripheral parting surface,the process comprises: cutting sheet stock of foamed resilientcross-linked polyolefin into preforms inherently having a somewhat roughnon-arcuate edge, said polyolefin being at least capable of beingsufficiently thermoformed, or molded, to allow such edge to be formedinto an arcuate smooth edge, and said preforms, in plan view, having inone embodiment a peripheral configuration, when in a relaxed condition,substantially corresponding to the peripheral shape of the cavity inplan peripheral view; at about room temperature, positioning asufficient number of said preforms and, optionally, at least one insertinto a mold portion so that upon closing and heating the mold saidpreform or preforms and optional insert are placed in gentle compressivecontact with the cavity and are substantially confined within saidcavity without lateral projection into said peripheral parting surface;closing the mold and heating the closed mold for a sufficient period oftime to allow said non-arcuate, rough edge of said polyolefin to bethermoformed (heat formed) into a smooth, arcuate edge by contact withthe smooth arcuate edge of said mold cavity. When plural preforms areused and/or said optional insert is employed, the heating is sufficientto form a bonded unitary article.

In another embodiment, e.g. when the mold cavity is arcuate in planview, the preform can be cut as a generally rectilinear member and themember bent when positioning in the mold as opposed to the previousembodiment where it can be directly positioned in the mold cavitywithout significant bending.

In accordance with another feature of this invention an article ofmanufacture is provided which is a laminate comprised of a first portionof a foamed cross-linked polyolefin and a second portion of a foamedcross-linked polyolefin tenaciously bonded to said first portion, saidsecond portion having a density greater than said first portion. Inaccordance with another feature of this invention, such laminate carriesfastening means and is employed as a cushioning means, e.g. internallyof protective headgear like the jaw pad in a football helmet.

In accordance with another feature of this invention there is provided amethod for forming a solid self-supporting resilient cross-linked,foamed moldable polyolefin into a soft, energy-dissipating article in amold having partible mold portions, said mold, when in a closed positiondefining an article forming cavity and having a peripheral partingsurface, the method comprising: cutting stock of said polyolefin intopreforms; at about room temperature positioning a sufficient number ofsaid preforms, and, optionally, at least one insert, into said mold sothat upon closing said mold and heating same, said mold cavity is filledwith said sufficient number of preforms, and optional insert, tutwithout either, or any, laterally extending into said peripheral partingsurface; closing said mold and heating said closed mold containing saidpreforms, and optional insert, for a sufficient period of time for saidpreforms to conform to the adjacent mold cavity and said optionalinsert, when present, to bond to an adjacent portion of at least one ofsaid sufficient number of preforms and thereby form a bonded, singlepiece article which is substantially free of flashing.

In accordance with another feature of this invention, a laminatedarticle is provided comprising a first layer of foamed cross-linkedpolyolefin and a second layer of material overlaying said first layer ofpolyolefin, said second layer carrying perforate indicia and a portionof said first layer extending into said perforate indicia of said secondlayer. When different colored layers are employed the configuration canprovide attractive identification and aesthetic appeal.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent by reference to thedrawings wherein:

FIG. 1 illustrates the cutting of sheet stock into preforms;

FIG. 2 illustrates a mold, preforms and an insert which are used inaccordance with the method of this invention;

FIG. 3 is a three dimensional representation of one of the productsformed in accordance with the present invention;

FIG. 4 is a three dimensional representation of a protective head gearwhich is provided with the article shown in FIG. 3; 15 FIG. 5 is asectional view taken along the line 5--5 of FIG. 4;

FIG. 6 illustrates the preforms and an insert employed in accordancewith the present invention to form a thigh pad;

FIG. 7 is a three dimensional representation of a mold used to form sucha thigh pad;

FIG. 8 shows the mold of FIG. 7 in a closed position and containing thepreforms and insert of FIG. 6;

FIG. 9 is a three dimensional representation of a thigh pad formed inaccordance with the present invention;

FIG. 10 is a sectional view taken along the line 10--10 of FIG. 8 andshows a thigh pad being molded;

FIG. 11 is a sectional view taken along the line 11--11 of FIG. 8 alsoshowing the molding of a thigh pad.

DETAILED DESCRIPTION OF THE INVENTION

As previously indicated the present invention contemplates the use ofthe foamed cross-linked polyolefin (FXLPO) material in the form of asheet or bun-stock. Such materials are readily commercially availableand are supplied by Dynamit Nobel of America, Inc. under the trademarkTROCELLEN, and by Monarch Rubber Co., under their designation Evalite.The polyolefins can be homopolymers of ethylene or homopolymers ofpropylene and/or copolymers of ethylene and/or propylene withcopolymerizable monoolefinically unsaturated monomers such as, forexample, vinyl acetate. One such copolyxer which is widely commerciallyavailable is a copolymer of ethylene and vinyl acetate, typically withup to about 30% by weight of vinyl acetate as the comonomer. Thesematerials are cross-linked by irradiation or by the use of chemicalcross-linking agents such as the peroxides and hydroperoxides. Foamingis accomplished by using any of many well-known chemical or physicalfoaming agents. The (FXLPO) materials contemplated for use in thepresent invention obviously are not cross-linked to the extent that theyare no longer formable. That is, the materials employed should only bepartially cross-linked and the cross-linking should allow for thematerials to be put into a mold and possess sufficient moldability, ordeformability, when heated so that at least a rough cut edge can conform(flow or deform) to a smooth arcuate surface of the mold, whereby anarticle can be formed which has smooth edges rather than rough cutedges. These materials generally have high heat resistance, good fatigueresistance and good resistance to a wide variety of environmentalconditions. In general the densities of the foamed cross-linkedpolyolefins (FXLPO) employed can vary over a wide range. Quiteoutstanding results will be obtained using materials having densities inthe range of about 2 to about 10 or 12 pounds per cubic foot.

Referring to FIGS. 1-5, sheet stock 26 of the FXLPO material is firstcut, for example using a die cutter 22, to form preforms 28. Molding ofa preform, or a plurality of preforms either with or without the use ofan insert, is effected by the use of metallic partible molds,respectively 10 and 12. Partible mold portion 12 includes an articleforming cavity 18, which as seen in FIG. 2, is generally arcuate, orC-shaped, in plan view. Cavity 18 is so formed that its lower edges 20are smooth and rounded so as to produce a more comfortable andaesthetically appealing product. When in a closed position theperipheral parting surfaces 14 and 16 of the mold are brought intointimate contact with each other. Partible mold portion 10 is providedwith an inwardly (or downwardly) projecting molding surface 21 whichupon closing snugly nests within cavity 18 and defines an articlemolding surface.

At least one preform 28 is employed which, in plan view, has aperipheral configuration substantially corresponding to the peripheralshape of cavity 18 in plan view. That is both cavity 18 and preform 28are substantially the same in plan peripheral view. Alternatively,however, a preform can be cut which is generally a rectilinear preform30 by use of a suitable cutting die 24. When a rectilinear member 30 isemployed, it will need to be bent before it can be positioned withinmold cavity 18. This is in contrast to the use of the C-shaped preform28 which may be substantially directly placed within cavity 18. Ineither case, however, because of the cutting operation, the preforms aregenerally provided with rough cut edges 32. Of course, for aestheticpurposes and comfort when used in contact with the skin, these roughedges need to be formed into smooth rounded edges in the mold.

In referring to FIG. 2 alternate options of the present invention becomeapparent. In FIG. 2 plural preforms are employed, namely a preform 28and a preform 29 which generally is of lesser thickness. These preformsobviously can be tailored for preselected end uses by using FXLPOmaterials which have different densities. When different densities arenot desired, a single preform 28 may be employed.

FIG. 2 also illustrates the optional use of a insert 34 which integrallycarries suitable fastening means 36. Fastening means 36 can be any of anumerous variety of available fasteners, including metallic fastenershaving orifices for snapping engagement with complementary fasteningmeans on another article, or the fastening means can be Velcro material.There may, of course, be no need to employ any insert or an insert whichcarries fastening means depending on the desired end use.

In the embodiment set forth in FIG. 3, a soft, resilient,self-supporting energy dissipating jaw pad 42, which will be employedinside of a protective head gear such as, for example, football helmet38 is illustrated. Such a pad needs to possess optional insert 34 whichcarries appropriate fastening means 36. Generally, insert 34 may be ofany convenient material depending on the ultimate use including plastics(both thermoplastic and thermoset) or metals, for example aluminum, andpaperboard. The insert can also be a reinforcing mat such as a glassfiber reinforcing mat or a polymeric reinforcing mat such as apolyethylene terephthalate fibrous mat. The insert may, or may not,include the integral fastening means 36 depending on the ultimateproduct use. The insert may take the form of a sheet, either curvilinearor planar, a film or a fabric, either woven or nor-woven. Outstandingproducts have been produced in accordance with this invention by usinginserts whose resistance to flexure has been greater than that of theFXLPO material used for the preform(s), i.e. the insert generally willbe less elastic or more rigid. For the jaw pad example, the insert maybe a polyolefin, preferably a cross-linked polyolefin and most desirablya foamed cross-linked polyolefin but one which has slighter greaterdensity then the preform 28, and optional preform 29.

Preform 28 is positioned within cavity 18, and is overlayed withoptional preform 29. Insert 34 is then positioned, or overlayed, on topof preform 29. Partible mold 10 is then brought into contact with thelower partible mold portion 12. The article defining molding surface ofthe formed cavity (including the snugly nesting molding surface 21) andthe preform, or preforms, and optional insert, are selected sc that uponclosing the mold, preform 28, or optional preform 29 and the optionalinsert 34 are placed in gentle compressive contact with the cavity.Additionally, whether a single preform is used or plural preforms,either with or without an insert, the gently compressed material to bemolded and/or bonded is within the article defining surfaces of the moldand are substantially confined within the mold and its cavity formingsurface without laterally projecting into the peripheral partingsurfaces 14 and 16 of mold halves 10 and 12.

The closed mold containing the molding materials 28, 29, 34 is thenheated in any convenient manner such as, for example, in an air heatedoven. The molds can also be heated by putting them in contact with anysuitable heat transfer medium or for that matter designing the molds toallow the passage of a heat transfer medium therethrough. As previouslyindicated, it is generally desired to convert rough cut edges 32 to asmooth curved arcuate edge 33 by molding the rough cut edge 32 incontact with the smooth edge 20 of the cavity 18. Consequently, the moldand materials to be molded, are heated to a temperature and for a timeat least sufficient to effect that objective, that is for the rough edgeto be molded and formed into a curved smooth edge. Typically, theheating is done at a temperature in the range of about 250° F. to about500° F. for about 1 to about 20 minutes. During such heating not onlyare rough edges converted to smooth edges but in general the entirepreform 28 takes on the configuration of the molding surfaces andresults in the production of a much smoother aesthetically pleasingarticle.

After cooling, final article 42 is removed from the mold. This article,which is represented in the form of a C-shaped member, is employedinside of protective headgear like football helmet 38, as a safety andenergy absorbing member. Headgear 38 includes a rigid protective shell40 of a suitable polymeric material and the article 42 is disposedinternally of shell 40 as a jaw pad. The jaw pad 42 is attached to theshell 40 by suitable inter-engaging fastening means, generallydesignated 44, one part 46 of which is carried by the shell 40 and theother part 36 of which is carried by jaw pad 42. The fastening means 44can best be seen in FIG. 5 which shows the attachment of jaw pad 42 toshell 40 by the inter-engaging fastening means 46 and 36, respectively.In the preferred embodiment the fastening means 44 will be conventionalmetallic snap fasteners.

Thus from the above it will be apparent that the present method providesa technique whereby a variety of FXLPO materials, e.g. of varyingdensities, can be tenaciously heat bonded to each other and/or moldedinto finished articles having smooth surfaces. By properly selecting atleast one preform (or a plurality of preforms) either with or without aninsert, to fill the cavity so that the preform, or preforms and optionalinsert are placed in gentle compressive contact with the moldingsurfaces but are confined within the cavity and without laterallyprojecting into the peripheral parting surface, production economies areobtained. There is no flashing which must be removed because thematerials do not significantly enter the peripheral parting surface, orline, of the mold during molding.

Referring now to FIGS. 6-11, another embodiment of the invention isillustrated wherein a thigh pad 48 conventionally used with footballequipment is fabricated. The thigh pad is generally illustrated in FIG.9 and includes a somewhat centrally disposed recessed panel 64 and aslight annular collar 62. The thigh pad in transverse cross section isgenerally concave. Thigh pad 48 is formed from two preforms, best seenin FIG. 6, 50 and 52 respectively with the upper portions 54 of each ofthe preforms being somewhat larger than the lower, or bottom portions,56 and the sides thereof gradually tapering from upper portion 54 tolower portions 56. Preforms 50 and 52 are each formed from a foamedcross-linked polyolefin and the specific materials of each preform maybe the same or different. In addition to the preforms, an insert 58 isemployed with the insert having disposed along its longitudinaldimension a plurality of downwardly protruding ribs 60. In transversecross section, both through the main body portion of insert 58 andthrough ribs 60, the insert is upwardly concave. The preform, 50, whichis disposed upwardly of the upwardly concave insert generally will be ofa slightly smaller area than will the lower preform, 52.

Preforms 50 and 52 are cut from a stock with a cutting die and alsoinclude rough edges 33. Insert 58 is generally formed of a rigidnon-foamed material, preferably an organic polymer (such as, forexample, polyvinyl chloride or the like) or a metal (like aluminum) and,obviously, adds strength and rigidity to the thigh pad. Outstandingresults will be obtained using a rigid polyvinyl chloride insert, e.g. acurvilinear sheet with a thickness of about 1/16 to about 1/8 inch.Insert 58 becomes substantially totally enveloped and encapsulatedbetween preforms 50 and 52 and preforms 50 and 52 in turn becometenaciously peripherally bonded to each other and, depending on itscomposition, to insert 58 during the molding operation generallyillustrated in FIGS. 7, 8, 10 and 11.

The molds include partible mold halves, 66 and 68, which mold halves arepivotally mounted, as by rod 74, and can be closed and clamped by theclamping mechanism 76. The mold includes peripheral parting surfaces 70and 72, respectively. The preforms and insert are such that preforms 50and 52 are gently compressed within the mold cavity upon closing of themold halves. The preforms are also substantially confined within themolding cavity without lateral projection into the mold partingsurfaces, e.g. 70 and 72. This is best exemplified in FIGS. 10 and 11wherein it will be seen that upon first positioning the lower preform 52into the partible mold 66 and then, overlaying, insert 58 thereon,followed by the positioning of preform 50 thereover, the insert andpreforms are confined within the article defining surfaces of the moldcavity and do not project laterally into the mold parting surfaces. Uponheating, small portions of preforms 50 and 52 may tend to creep into themold parting surfaces, but if this happens the amount is soinsignificant that virtually no unacceptable flashing forms and that thefinal article 48 still does not need to be trimmed. The closed mold withthe insert and preforms are heated at a temperature for a timesufficient such that rough edges, like edges 33, can flow and form intothe smooth arcuate edges 78 by contact with the smooth curved moldingsurfaces.

Because the preform or preforms, and optional inserts, are allpositioned in a mold while the insert and preforms are at roomtemperature, there is little difficulty in positioning them in theproper place because they are not in a heated or sticky state whenhandled. This provides an improvement over the practices notedpreviously. This convenient indexing is itself a great benefit but italso appears that undesired air entrapment is also virtually eliminated.

It will be recalled that hip pad configurations were indicated to have araised centrally located portion but because of the handling of heatedpanels it is expensive and difficult to form raised portions on the hippad by inserting a material which is not the same as the material of thebase portion. The difficulty in handling a tacky heated sheet stockinsert is the cause of the problem. In accordance with the presentinvention, because the FXLPO materials are positioned within the mold atroom temperature, this problem is obviated. The method provides anopportunity to easily form the raised portions of a hip pad from amaterial which is not the same as the base material.

Based on the foregoing, it will be apparent that many options exist fortaking advantage of the present invention. For example, and, althoughnot shown, perhaps best appreciated by reference to the embodimentdescribed with respect to FIG. 2, at least one of the preforms 29 and/orthe insert 34 can be provided with perforate indicia so that uponclosing of the mold, and molding by heating, foamed cross-linkedpolyolefin from a different preform can enter into the perforateindicia. This perforate indicia can take the form of any suitableopening, or openings, which defines lettering and/or a suitable design.The lettering obviously can be used for identification and/oradvertising purposes. The design can similarly be a manufacturer's logoand function similarly. In this way, and especially in the case whendifferent colors are used in the preform and/or insert, the laminatedconfiguration can provide an attractive identification and aestheticallyappealing structure. Thus, for example, if it were desired to form, inaccordance with FIG. 2, an article (other than a jaw pad or one needinginsert 34) having some distinctive indicia thereon, preform 29 wouldhave an opening or openings made through it. The opening(s) would, forexample, be a name so that when molded FXLPO material from preform 28would enter the openings and provide a contrasting indicia on the uppersurface of preform 29. Use of contrasting colors for preforms 29 and 28provides an opportunity for many appealing structures.

In a like manner, insert 34 could be provided with perforate indicia(either with or without fastening means 36) so as to allow theadjacently downwardly FXLPO material from a preform 29 (or 28 dependingon how many are used) to form the identification or design indicia byentering and generally heat bonding to the indicia defining surfaces.

While no vents are shown in the molds, it is generally preferred toprovide appropriately arranged small vent holes. Additionally, inpracticing this invention, it has been found that non-cross linkedfoamed polyolefins are generally not satisfactory for the presentpurposes because they contract and soften and flow when heated.Outstanding shock energy absorbing materials have been produced withmaterials indicated above and without the utilization of anypolyurethane or foamed polyurethane or any precursors to a polyurethaneor foamed polyurethane. Additionally it should be noted that tenaciousteat bonding between FXLPO materials is effected without the necessityfor dipping any of the preforms or inserts into organic peroxidesolutions.

Having described the invention it will of course be apparent thatmodifications are possible which pursuant to the patent statutes andlaws do not depart from the spirit and scope thereof.

What is claimed is:
 1. A method for forming a soft, resilient,self-supporting, energy-dissipating article in a mold having partiblemold portions, said mold, when in a closed position, defining an articleforming cavity which includes a smooth arcuate edge and said mold havinga peripheral parting surface, said method comprising: cutting sheetstock of foamed, cross-linked polyolefin into preforms having a roughedge, said polyolefin being at least capable of being sufficientlythermoformed to allow a rough edge to be formed into a smooth edge, andsaid preforms, in plan view, having a peripheral configurationsubstantially corresponding to the peripheral shape of the cavity inplan peripheral view; at about room temperature, positioning asufficient number of said preforms and, optionally at least one insert,into a mold portion so that upon closing and heating the mold saidpreform, or preforms, and optional insert are placed in compressivecontact with the cavity and are substantially confined within saidcavity without laterally projecting into said peripheral partingsurface; heating a closed mold containing said preforms and optionalinsert for a sufficient period of time to allow said rough edge of saidpolyolefin to be formed into a smooth edge by contact with said smoothedge of said mold cavity and wherein, when plural preforms are used,and/or said optional insert is employed, said heating is done at asufficient temperature for a sufficient time to form a bonded unitaryarticle.
 2. The method of claim 1, wherein a single preform is sopositioned in said mold portion.
 3. The method of claim 1 wherein atleast two such preforms are so positioned.
 4. The method of claim 1wherein at least one insert is positioned in a mold portion.
 5. Themethod of claim 1 wherein said insert carries integral fastening means.6. The method of claim 4 wherein said insert is a nonfoamed rigidorganic polymer.
 7. The method of claim 4 wherein said insert is afoamed, cross-linked polyolefin having a greater density than thedensity of said preform.
 8. The method of claim 7 wherein said preformhas a density of about 2 to about 8 #/Ft³ and said insert has a densityin excess of about 4 #/Ft³.
 9. The method of claim 1 wherein saidpolyolefin is a closed cell polyethylene.
 10. The method of claim 5wherein said preform and said insert are generally C-shaped.
 11. Themethod of claim 1 wherein said heating is also done for a sufficientperiod of time that the outwardly exposed surface of said preformbecomes smoother.
 12. A method for forming a solid self-supportingresilient cross-linked, foamed moldable polyolefin into a soft,energy-dissipating article in a mold having partible mold portions, saidmold, when in a closed position defining an article forming cavity andhaving a peripheral parting surface, the method comprising: cuttingstock of said polyolefin into preforms; at about room temperaturepositioning a sufficient number of said preforms, and, optionally, atleast one insert, into said mold so that upon closing said mold andheating same, said mold cavity is filled with said sufficient number ofpreforms, and optional insert, but without either laterally extendinginto said peripheral parting surface; closing said mold and heating saidclosed mold containing said preforms, and optional insert, for asufficient period of time for said preforms to conform to the adjacentmold cavity and said optional insert, when present, ±o bond to anadjacent portion of at least one of said sufficient number of preformsand thereby form a bonded, single piece article, said method therebyproducing ar article which is substantially free of flashing.
 13. Themethod of claim 12 wherein said sufficient number of preforms is one.14. The method of claim 12 wherein said sufficient number of preforms,and said optional insert fill said mold cavity at about room temperaturewhen said mold is closed and prior to said heating.
 15. The method ofclaim 13 wherein an insert is positioned in said mold so as to beenveloped by at least two contacting preforms.
 16. The method of claim12 wherein at least one insert is employed, said insert having meansthereon for fastening said insert and single piece article to a membercarrying complementary means for interengageably fastening to saidinsert fastening means.
 17. The method of claim 16 wherein said insert'sfastening means comprises an orifice.
 18. The method of claim 12 whereinneither said optional insert or any of said sufficient number ofpreforms is formed of a polyurethane or a polyurethane formingprecursor.
 19. The method of claim 12 wherein (i) at least one of saidnumber of preforms and/or said insert are provided with perforateindicia and wherein said perforate indicia carrying preform and/orinsert are so positioned in said mold that upon closing said mold andheating, foamed cross-linked polyolefin from a preform, enters into saidperforate indicia.
 20. The method of claim 19 wherein said foamedcross-linked polyolefin which enters said perforate indicia is of acolor different than said preform and/or insert provided with saidperforate indicia.
 21. A method for molding a foamed cross-linkedpolyolefin in a mold having partible mold portions comprisingpositioning said foamed cross-linked polyolefin while substantially atabout room temperature in a cavity portion of said mold, closing saidpartible mold portions and heating said mold and said polyolefin so asto mold and conform outer portions of said polyolefin to the surface ofthe mold cavity, the amount of polyolefin being such that during saidheating substantially no polyolefin extends into the mating partingsurfaces of the closed partible mold portions.
 22. The method forforming a molded foamed cross-linked polyolefin article which issubstantially free of flashing in a mold having partible mold halveswhich when closed define a cavity and a contiguous peripheral moldparting line comprising: positioning, while at substantially roomtemperature, foamed cross-linked polyolefin into a cavity portion ofsaid mold; closing said mold; heating said mold for a sufficient periodof time to form said article.
 23. The method of claim 22 wherein theamount of polyolefin material positioned in the mold is insufficient tosubstantially extend into said parting line upon closing said mold andheating.